Traction unit for electric model railways

ABSTRACT

In a traction unit for electric model railways consisting of a two-phase synchronous electric motor and an electronic unit for supplying the electric motor with two-phase pulse voltages from a feed voltage taken from the rails, an elastic clutch and, preferably, also a torque limiter is provided in the mechanical connection by means of which the electric motor drives the traction wheels, whereby the modeling range is extended to the use of quite low frequencies and, thus, to small revolution numbers of the traction wheels.

United States Patent Halmai et a1.

[45] Mar. 7, 1972 [54] TRACTION UNIT FOR ELECTRIC MODEL RAILWAYS AttilaHalmai; Gem Halmai, both of Budapest, Hungary Nikex NehizipariKulkereskedelmi Vallalat, Budapest, Hungary Dec. 16, 1969 inventors:

Assignee:

Filed:

Appl. No.:

Foreign Application Priority Data Dec. 28, 1968 Hungary ..HA-865 U.S.Cl..l04/148, 105/131 Int. Cl ..B61b 11/00 Field oiSearth ..104/l48;105/130, 131; 192/55 References Cited UNITED STATES PATENTS 1,041,86710/1912 Pieper u es/ 130 1,283,787 11/1918 Jencick ..105/13l 1,596,9398/1926 "Mrongovius et al. ..l05/130 1,791,016 2/1931 Sundh 192/551,925,278 9/1933 Patonm. 192/55 2,233,705 3/1941 Hook.... ....192/553,205,989 9/1965 Mantey.... ..192/55 Primary Examiner-Drayton E. HoffmanAttorney-Young & Thompson [57] ABSTRACT in a traction unit for electricmodel railways consisting of a two-phase synchronous electric motor andan electronic unit for supplying the electric motor with two-phase pulsevoltages from a feed voltage taken from the rails, an elastic clutchand, preferably, also a torque limiter is provided in the mechanicalconnection by means of which the electric motor drives the tractionwheels, whereby the modeling range is extended to the use of quite lowfrequencies and, thus, to small revolution I numbers of the tractionwheels.

3 Claims, 6 Drawing Figures PAIENTEDI'IAR H972 I 3.646.892

' sum 1 OF 2 Fig.2

INVENTORY Arr/1.4 r /ALMA/ 652.4 /flLMA/ BY 71-7! MW ATTORNEYS TRACTIONUNIT FOR ELECTRIC MODEL RAILWAYS This invention relates to tractionunits for electric model railways of the type having traction wheelsarranged for running on a track the rails of which form electricconductors, and underframe supported by said traction wheels, anelectric motor on said underframe for driving said traction wheels bymeans of a mechanical connection, and an electronic unit arranged forbeing fed by means of said rails for supplying said electric motor witha two-phase pulse voltage.

As is known, model railways are destined to simulate occurrences such asacceleration and deceleration of real railway running stock, e.g.,trains or single locomotives. It has been suggested to employ two-phasesynchronous motors fed with pulse voltages supplied by electronic unitswhich operate to select a certain frequency from a series of frequenciesfrom rails on which a traction unit is running, and to transform suchfrequencies into pulse voltages of prescribed frequencies suitable foroperating the two-phase synchronous motors at desired speeds.

Traction units equipped with such motors are capable of simulating realacceleration and deceleration phenomena which, otherwise, would beimpossible due to the basic difference between the friction to weightrelations of real railway running stock and of model railways,respectively.

The only deficiency of the known system is that with very low speeds,that is with very low frequencies which are necessary to simulate theacceleration of a railway running stock at the start or its decelerationat stopping, the two-phase synchronous motor will not operatecontinuously but jump from one phase position to another. Apart fromsuch jumping operation being unsuitable for simulating the operation ofa running real railway stock it may also result in slipping of thetraction wheels. Then, however, the running stock will not move at all.

The main object of the present invention is to eliminate suchdeficiencies and to extend the range of control of model railway systemsof the aforesaid type to the domain of very low speeds. The basic ideaof the invention consists in charging with the motive force yielded byone jump of the motor a mechanical system which is capable of yieldingthe stored energy continuously during the span between two subsequentjumps. Thereby, a continuous mode of operation even in the range of verylow frequencies may be obtained. According to the invention, this isobtained by providing an elastic drive connection or clutch in themechanical connection which connects the two-phase synchronous electricmotor with the traction wheels of a traction unit. Obviously, when theelectric motor makes ajump under the action of a very low frequencypulse voltage, the elastic clutch becomes tensioned because the tractionwheels cannot follow the angular displacement of the driving shaft ofthe electric motor. When the tension of the elastic clutch is highenough to rotate the traction wheel, the energy stored in it becomesgradually discharged so that the traction wheels, instead of slipping,will slowly and continuously rotate.

The invention will be described in closer details by taking reference tothe accompanying drawings which show, by way of example, two embodimentsof the new traction unit.

FIG. 1 is a diagrammatic view of the first exemplified embodiment of themodel railway traction unit of the present invention.

FIG. 2 is a diagrammatic view of the second exemplified embodiment ofthe model railway traction unit of the present invention.

FIG. 3 is a diagrammatic view of the model railway traction unit of thepresent invention.

FIG. 4 is a view in vertical section illustrating an elastic driveconnection.

FIG. 5 is a view in vertical section illustrating an elastic driveconnection with a torque limiter.

FIG. 6 is a view in vertical section illustrating a magnetic hysteresiscoupling.

Same reference characters throughout the drawings.

refer to similar details Referring to the drawings, reference character10 designates one rail of a model railway track with a traction unitaccording to the invention arranged on it. The traction unit consists oftraction wheels 12 supporting an underframe 14. The underfrarne 14carries a two-phase synchronous electric motor M which is mechanicallyconnected with the traction wheels 12. The electric motor M is fed by anelectronic feed unit F which, in turn, is fed via the rails 10 by meansof a running collector 16.

According to the invention, the mechanical connection between theelectric motor M and the traction wheels 12 comprises an elastic clutch.

With the exemplified embodiment shown in FIG. 1, the elastic clutchdesignated by reference character 18 is of the expansion coupling type.

In addition to the elastic clutch 18, the exemplified embodiment shownin FIG. 1 comprises also a torque limiter 20 which, however, might besubstituted by the frictional contact between the traction wheels 12 andthe rails 10. Then, the torque limiter 20 may be dispensed with.

In operation, the rails 10 of the track carry various frequen cies oneof which is associated with the traction unit described above. Thisfrequency is pulsed from a not represented control station andtransformed by the feed unit F in e.g., square voltage pulses of adesired frequency used for feeding the twophase synchronous electricmotor M. Rotation of the motor M causes the mechanical connectionbetween electric motor M and traction wheel 12 to rotate as well. Uponsuch rotation, the elastic clutch 18 becomes tensioned whereby thetorque exerted by the electric motor M is first stored in the elasticclutch l8 and then released by it and clamped. The torque limiter 20ensures that the masses of the traction unit and the rolling stockcoupled with it are permitted to prevail only until a torque value isobtained where the torque limiter 20 begins to slip.

FIG. 3 illustrates a toy locomotive with a pair of bogies, one of whichis provided with the elastic connection between an electric motor M andtraction wheels 12. The other bogie has the running collector l6incorporated in it. Between the electric motor M and the runningcollector 16 there is the electronic feed unit F which serves forconverting the input DC voltage with a superposed pair of carrierfrequency voltages from the track 10 into a pair of square pulsevoltages of required frequencies and phase shifts. This circuit Foperates in a known manner.

FIGS. 4 and 5 show details of the mechanical connection between thetraction wheels 12 and the electric motor M in vertical sectional viewstaken along the lines lV-IV and V- V, respectively, of FIG. 3.

FIG. 4 illustrates one form of the elastic connection 18 which consistsof a gear loosely supported on the axle of traction wheels 12 andconnected with the latter by means of a helical spring so that torque istransmitted from the gear to the traction wheels 12 by means of thespring which permits an elastic transmission therebetween.

FIG. 5 shows the torque limiter 20 with a horizontal axle on which apinion is mounted for meshing with the aforesaid gear of the elasticconnection 18. The axle of the pinion supports a friction disc, theinside surface of which engages with the outside surface of acircular-arc tooth gear. This, in turn, meshes with a pinion on thevertically arranged shaft of the electric motor M. The frictionalconnection between the circular-arc tooth gear and the friction disk isensured by a helical spring disposed between the pinion and the former.

in operation of the elastic connection shown in FIGS. 4 and 5, the shaftof the electric motor M rotates the pinion at its lower end which, inturn, rotates the circular-arc tooth gear. This is pressed by its spiralspring against the inside surface of the friction disk so that thelatter is rotated together with the former. Thus, the pinion on theshaft of the friction disk is set into rotation as well as rotates, inturn, the gear of the elastic connection 18. The spiral spring of thelatter is tensioned until the static resistance of the traction wheels12 is overwhelmed and the latter begin to rotate. Then, the toylocomotive is propelled on the track 10. Should the resistance of thetraction wheels 12 be greater than the frictional force between the diskof the torque limiter 20 and its circular-arc tooth gear determined bythe strength of its helical spring, the circulararc tooth gear will slipon the friction disk as described in connection with the embodiment ofFIG. 1.

The exemplified embodiment shown in FIG. 2 differs from the previous onein that the elastic clutch l8 and the torque limiter 20 are replaced bya single magnetic hysteresis coupling 22 which is actually a combinationof both the elastic clutch l8 and the torque limiter 20.

The operation of the exemplified embodiment according to FIG. 2 isessentially the same as that of the previous exemplified embodiment. Theonly difference is due to the elastic clutch l8 and the torque limiter20 of the first embodiment being replaced by the magnetic hysteresisclutch 22 which means that the function of energy storing and releasingas well as torque limiting is performed by one and the same unit.

FIG. 6 shows with greater specificity the embodiment of the invention ofFIG. 2 where the functions of the elastic connection 18 shown in FIGS. 1and 4 and the torque limiter 20 shown in FIGS. 1 and 5 are performed bya single unit formed by a magnetic hysteresis coupling 22. Here, thegear of the elastic coupling 18 of the previous embodiment carries asleeve made of hysteresis material whereas the shaft of the tractionwheels 12 carries a cylindrical body of magnetic material. I

In operation, the coupling between the gear and the traction wheelsshaft is obtained by the magnetic field which is generated by the mutualrotation of the sleeve and the cylindrical body. Obviously, thegeneration of such magnetic field requires a mutual displacement of bothcomponent parts which corresponds to the function of the elasticconnection 18. On the other hand, if the resistance against motion ofthe toy locomotive exceeds a certain value, the field between the sleeveand the cylindrical body will not be strong enough to rotate thetraction wheels in which case the sleeve will rotate around thestationary cylindrical body which corresponds to the function of thetorque limiter shown in FIG. 5.

What we claim is:

1. In combination with a miniature electric model railway including amodel electric locomotive having a two phase synchronous motor fordriving locomotive traction wheels supplied with pulse voltages ofprescribed frequencies by an electronic feed unit operative to select afrequency from frequencies provided thereto by model railway rails, animproved traction unit mounted on said model locomotive and adapted toprovide a continuous drive torque to said traction wheels when lowfrequency pulse voltages from said electronic feed unit cause said twophase synchronous motor to cease continuing operation and to jumpbetween phase positions, comprising an input drive unit mechanicallyconnected to said two phase motor to be driven thereby, and an outputdrive unit connected to drive said traction wheels and mechanical energystorage means operating to couple said input drive unit to said outputdrive unit, said mechanical energy storage means operating to storemechanical energy yielded by each jump of the synchronous motor and togradually discharge the stored energy continuously to said output driveunit during the span between successive jumps of said synchronous motor.

2. The combination of claim 1 wherein said mechanical energy storagemeans includes a mechanical expansion coupling connected between saidinput and output drive units, said output drive unit including a torquelimiter to limit the torque applied to said traction wheels by saidtraction unit.

3. The combination of claim 1 wherein said mechanical energy storagemeans constitutes a magnetic field coupling said input drive unit tosaid output drive unit, said input and output drive units being formedof material to create said magnetic field and provide a magnetichysteresis coupling.

1. In combination with a miniature electric model railway including amodel electric locomotive having a two phase synchronous motor fordriving locomotive traction wheels supplied with Pulse voltages ofprescribed frequencies by an electronic feed unit operative to select afrequency from frequencies provided thereto by model railway rails, animproved traction unit mounted on said model locomotive and adapted toprovide a continuous drive torque to said traction wheels when lowfrequency pulse voltages from said electronic feed unit cause said twophase synchronous motor to cease continuing operation and to jumpbetween phase positions, comprising an input drive unit mechanicallyconnected to said two phase motor to be driven thereby, and an outputdrive unit connected to drive said traction wheels and mechanical energystorage means operating to couple said input drive unit to said outputdrive unit, said mechanical energy storage means operating to storemechanical energy yielded by each jump of the synchronous motor and togradually discharge the stored energy continuously to said output driveunit during the span between successive jumps of said synchronous motor.2. The combination of claim 1 wherein said mechanical energy storagemeans includes a mechanical expansion coupling connected between saidinput and output drive units, said output drive unit including a torquelimiter to limit the torque applied to said traction wheels by saidtraction unit.
 3. The combination of claim 1 wherein said mechanicalenergy storage means constitutes a magnetic field coupling said inputdrive unit to said output drive unit, said input and output drive unitsbeing formed of material to create said magnetic field and provide amagnetic hysteresis coupling.